WO2010061555A1

WO2010061555A1 - Liquid crystal display device and method for manufacturing liquid crystal display device tft substrate

Info

Publication number: WO2010061555A1
Application number: PCT/JP2009/006245
Authority: WO
Inventors: 美崎克紀
Original assignee: シャープ株式会社
Priority date: 2008-11-28
Filing date: 2009-11-19
Publication date: 2010-06-03
Also published as: CN102227678A; US20110227817A1; CN102227678B

Abstract

A liquid crystal display device having a high display quality can be manufactured with a high efficiency. The liquid crystal display device includes a plurality of pixels each having a reflection region and a transparent region. The liquid crystal display device includes: a TFT substrate having a first transparent layer and a second transparent layer which are formed on a TFT and a pixel electrode formed on the first or the second transparent layer; an opposing substrate; and a liquid crystal layer. A first sub pixel electrode formed in the reflection region is arranged on the plane of the second transparent layer and a second sub pixel electrode formed in the transparent region is arranged on the plane of the first transparent layer. The second transparent layer has a first protrusion formed so as to protrude toward the liquid crystal layer side as compared to the first sub pixel electrode and to surround the first and the second sub pixel electrode.

Description

Liquid crystal display device and method for manufacturing TFT substrate of liquid crystal display device

The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly to an active matrix liquid crystal display device using a switching element such as a thin film transistor (TFT) and a manufacturing method thereof.

In recent years, there has been a demand for higher performance of liquid crystal display devices. For mobile phones and portable electronic devices, performance that is more suitable for lower power consumption and outdoor use is strongly demanded. Pixels having light reflectivity are sufficient to satisfy these performances. Development of a reflective liquid crystal display device that uses an electrode to display with external light and does not require a light source device has been underway.

A pixel electrode (reflective electrode) is formed on a TFT substrate of a reflective liquid crystal display device by a metal thin film having high reflectivity. The reflective liquid crystal display device reflects natural light and electric light incident from the display screen side on a TFT substrate, and uses the reflected light as a light source for liquid crystal display. The reflective electrode has an uneven surface. The uneven surface of the reflective electrode can be obtained by forming the reflective electrode on a photosensitive resin film having an uneven surface. By reflecting light incident from the display screen side irregularly on the uneven surface of the reflective electrode, a reflective liquid crystal display device with high brightness and wide viewing angle is realized.

Examples of liquid crystal display devices that perform display using reflected light are described in Patent Document 1 and Patent Document 2.

In the liquid crystal display device of Patent Document 1, the colored layer and the multi-gap portion are provided on the pixel substrate side, and a decrease in aperture ratio and a decrease in yield due to misalignment between the pixel substrate and the counter substrate are prevented. . Further, in this liquid crystal display device, a multi-gap portion, which is an upper layer of the colored layer, is formed on the opening, and a contact hole is provided inside the periphery of the opening. Thereby, since the contact hole can be formed simultaneously with the formation of the multi-gap portion, the number of manufacturing steps is reduced. In addition, since the step between the colored layer and the multi-gap portion is not formed in the contact hole, the conduction failure of the transparent electrode is reduced, and the aperture ratio in display using reflected light is improved. Further, since the contact hole is arranged in the opening, the reduction of the colored area accompanying the increase in pixel density is prevented, and display with high definition and high saturation becomes possible.

The liquid crystal display device described in Patent Document 2 is a reflection / transmission type liquid crystal display device, and includes a transmission region and a reflection region provided for each pixel, and a vertical alignment type liquid crystal layer provided between a pair of substrates. An interlayer insulating film provided on one of the pair of substrates and having an opening, and a rivet provided at the center of the transmission region in one of the pair of substrates. The orientation of the liquid crystal molecules in the liquid crystal layer when no voltage is applied is regulated by the rivets and the inclined surfaces of the interlayer insulating film. Therefore, a discontinuous region in which the alignment direction is discontinuous occurs between the liquid crystal molecules aligned by the rivet and the liquid crystal molecules aligned by the inclined surface. The liquid crystal display device of Patent Document 2 includes a light shielding unit for shielding light that has passed through the discontinuous region so as not to reach the observer.

In such a vertical alignment type liquid crystal display device having a transmissive region and a reflective region, the ratio of the cell gap of the transmissive region (the thickness of the liquid crystal layer) to the cell gap of the reflective region is set to 2: 1. Is desirable. For this reason, in general, a transparent resin layer called white is disposed only in the reflective region, and adjustment is made so that the cell gap ratio is as described above.

JP 2006-30951 A JP 2005-331926 A

An example of a reflection / transmission type liquid crystal display device will be described with reference to FIGS. FIG. 12 is a plan view schematically showing the configuration of one pixel of the reflective / transmissive liquid crystal display device 100. FIGS. 13 (a) and 13 (b) are views of the liquid crystal display device 100 in FIG. FIG. 4 is a cross-sectional view illustrating a configuration of a cross section taken along the line −A ′ and a cross section along the line BB ′. 14 to 16 are cross-sectional views showing a method for manufacturing the liquid crystal display device 100.

The liquid crystal display device 100 includes a plurality of pixels 10 arranged in a matrix, a plurality of signal lines (drain bus lines) 12 extending in the vertical direction (vertical direction in FIG. 12) along the boundaries of the pixels 10, and a horizontal direction. And a plurality of scanning lines (gate bus lines) 14 extending in the left-right direction in FIG. As shown in FIG. 12, each pixel 10 is surrounded by two adjacent signal lines 12 and two scanning lines 14. It is assumed that the boundary of each pixel 10 is on the center line of the signal line 12 and the scanning line 14.

The pixel 10 includes two transmissive regions 16 (the upper transmissive region is 16a and the lower transmissive region is 16b) and one reflective region 17 sandwiched between the two

transmissive regions

16a and 16b. Yes. The pixel electrode 20 of the pixel 10 includes a sub-pixel electrode 20a in the transmissive region 16a, a sub-pixel electrode 20b in the transmissive region 16b, and a sub-pixel electrode 20c in the reflective region 17. The sub pixel electrode 20a and the sub pixel electrode 20c, and the sub pixel electrode 20b and the sub pixel electrode 20c are connected to each other by a part of the pixel electrode 20.

A TFT 18 is disposed near the intersection of the signal line 12 and the scanning line 14 in the lower left part of the pixel 10. The gate electrode of the TFT 18 is connected to the scanning line 14, the drain electrode is connected to the signal line 12, and the source electrode is connected to the sub-pixel electrode 20b. A storage capacitor line (Cs line) 15 extends in the left-right direction below the reflection region 17 of the pixel 10. A reflective layer 25 is formed between the auxiliary capacitance line 15 and the sub-pixel electrode 20c. The reflective layer 25 is electrically connected to the source electrode of the TFT 18 and functions as an intermediate electrode. The auxiliary capacitance line 15 under the reflective layer (intermediate electrode) 25 functions as the auxiliary capacitance electrode 15c, and the auxiliary capacitance of the pixel 10 is formed between the reflective layer 25 and the auxiliary capacitance electrode 15c.

13A is a cross-sectional view of the reflective region 17, and FIG. 13B is a cross-sectional view of the transmissive region 16a. As shown in FIG. 13, the liquid crystal display device 100 includes a TFT substrate 30, a counter substrate 40, and a liquid crystal layer 50 disposed between the TFT substrate 30 and the counter substrate 40. The liquid crystal layer 50 is a vertical alignment type liquid crystal layer including liquid crystal molecules having negative dielectric anisotropy.

The TFT substrate 30 includes a glass substrate 31, a gate insulating layer 32 formed on the glass substrate 31, a protective layer 33 formed on the gate insulating layer 32, and a color filter (CF ) 34 and a transparent insulating layer (JAS) 35 formed on the color filter 34. A transparent resin layer 36 is formed on the transparent insulating layer 35 in the reflective region 17, and a sub-pixel electrode 20 c is formed on the transparent resin layer 36. In the

transmissive regions

16 a and 16 b, the

subpixel electrodes

20 a and 20 b are formed on the transparent insulating layer 35 without forming the transparent resin layer 36. By arranging the transparent resin layer 36 only in the reflective region 17, the ratio of the cell gap of the transmissive region 16 to the cell gap of the reflective region 17 is set to 2: 1.

The auxiliary capacitance electrode 15 c in the reflective region 17 is formed between the glass substrate 31 and the gate insulating layer 32, and the reflective layer 25 is formed between the gate insulating layer 32 and the protective layer 33. The reflection layer 25 is provided with irregularities to diffusely reflect light. The unevenness is formed by reflecting an opening or a depression formed in the lower storage capacitor electrode 15c.

The TFT 18 shown in FIG. 12 is also formed between the gate insulating layer 32 and the protective layer 33. The TFT 18 has an operating semiconductor layer made of, for example, amorphous silicon (a-Si) constituting the channel of the TFT 18 and an ohmic contact layer that is an n ⁺ -Si layer. The ohmic contact layer is connected to the source electrode and the drain electrode, and the source electrode is connected to the upper subpixel electrode through a contact hole formed by opening the protective layer 33, the color filter 34, and the transparent insulating layer 35. 20b is electrically connected. The source electrode is also electrically connected to the reflective layer 25 in the reflective region 17, and the reflective layer 25 is formed by opening a protective layer 33, a color filter 34, a transparent insulating layer 35, and a transparent resin layer 36. It is electrically connected to the upper sub-pixel electrode 20c through the contact hole.

As shown in FIGS. 12 and 13, projections (ribs) 27 are formed around the

transmission regions

16 a and 16 b and the reflection region 17 so as to surround the

sub-pixel electrodes

20 a, 20 b, and 20 c, respectively. . The protrusion 27 has a function of aligning liquid crystal molecules toward the inside of the

transmissive regions

16 a and 16 b and the reflective region 17.

The counter substrate 40 includes a glass substrate 41, a counter electrode 42 formed on the liquid crystal layer 50 side of the glass substrate 41, and protrusions (ribs) 45 formed at three locations on the surface of the counter electrode 42 on the liquid crystal layer 50 side. (45a, 45b, and 45c). The

protrusions

45a, 45b, and 45c are formed at the upper portions of the center positions of the

sub-pixel electrodes

20a, 20b, and 20c, respectively.

The cell gap (the distance between the sub-pixel electrode 20c and the counter electrode 42 or the thickness of the liquid crystal layer 50 sandwiched between both electrodes) in the reflective region 17 is, for example, 1.7 μm, and in the

transmissive regions

16a and 16b. The cell gap (distance between the

sub-pixel electrodes

20a and 20b and the counter electrode 42, or the thickness of the liquid crystal layer 50 sandwiched between both electrodes) is, for example, 3.4 μm. Thus, the cell gap between the

transmissive regions

16 a and 16 b is twice as thick as the cell gap of the reflective region 17.

The

protrusions

45a, 45b, and 45c, together with the protrusion 27 of the TFT substrate 30, control the alignment of the liquid crystal molecules in the transmissive region 16a, the transmissive region 16b, and the reflective region 17 in a radial manner around the

protrusions

45a, 45b, and 45c. Functions as a means. The protrusion 45c extends from the counter electrode 42 so as to be in contact with the sub-pixel electrode 20c, and also serves as a spacer for keeping the cell gap constant.

Next, a method for manufacturing the liquid crystal display device 100 will be described with reference to FIGS. 14A to 14E and 15F to 15I are cross-sectional views showing a method of manufacturing the TFT substrate 30 of the liquid crystal display device 100. FIGS. b) is a cross-sectional view illustrating a method of manufacturing the counter substrate 40 of the liquid crystal display device 100. FIG. In each figure, the cross section of the reflection region 17 (corresponding to the A-A 'cross section in FIG. 12) is shown on the left side, and the cross section of the transmission region 16a (corresponding to the B-B' cross section in FIG. 12) is shown on the right side.

In manufacturing the TFT substrate 30, first, Al (aluminum) or an Al alloy is laminated on the entire upper surface of the glass substrate 31 which is a transparent insulating substrate to a thickness of, for example, 130 nm by sputtering. If necessary, a protective film such as SiOx may be formed on the upper surface of the glass substrate 31 before lamination. Next, Ti (titanium) or a titanium alloy is laminated to a thickness of, for example, 70 nm on the laminated Al or the like by sputtering. Thereby, a metal layer having a thickness of about 200 nm is formed. Here, instead of Ti, Cr (chromium), Mo (molybdenum), Ta (tantalum), W (tungsten), or an alloy of these metals can be used. In addition, instead of Al, a material containing one or more of Nd (neodymium), Si (silicon), Cu (copper), Ti, W, Ta, and Sc (scandium) may be used.

Thereafter, a resist layer is formed on the metal layer, exposed through a first mask (photomask or reticle, hereinafter simply referred to as a mask) to form a resist mask, and dry etching using a chlorine-based gas. The metal layer is patterned to form the auxiliary capacitance electrode 15c as shown in FIG. At this time, the scanning line 14, the auxiliary capacitance line 15, and the gate electrode of the TFT 18 are also formed at the same time. At this time, an opening or a depression is formed in the auxiliary capacitance electrode 15c.

Next, as shown in FIG. 14B, for example, a silicon nitride film (SiN) is formed on the entire surface of the substrate to a thickness of about 400 nm by plasma CVD to obtain the gate insulating layer 32. Next, in order to form an operating semiconductor layer of the TFT 18, for example, an amorphous silicon (a-Si) layer (not shown) is laminated on the entire surface of the substrate to a thickness of about 30 nm by plasma CVD. Further, in order to form a channel protective film (etching stopper) of the TFT 18, for example, a silicon nitride film (SiN) (not shown) is formed with a film thickness of about 150 nm on the entire surface of the substrate by plasma CVD.

Next, after a photoresist is applied to the entire surface of the substrate by a spin coat method or the like, back exposure is performed from the glass substrate 31 side using the scanning lines 14, auxiliary capacitance lines 15, and auxiliary capacitance electrodes 15c as a mask. Thereafter, by dissolving the exposed resist layer, a resist pattern is formed in a self-aligned manner on the scanning line 14, the auxiliary capacitance line 15, and the auxiliary capacitance electrode 15c.

The resist pattern is further exposed from the forward direction (on the side opposite to the glass substrate 31) through the second mask to leave the resist layer only on the region where the channel protective film is to be formed. . Thereafter, by using this resist layer as an etching mask, the silicon nitride film is dry-etched using a fluorine-based gas to form a channel protective film. As shown in FIG. 14B, the channel protective film does not remain on the auxiliary capacitance electrode 15c.

Next, after cleaning the surface of the amorphous silicon layer using dilute hydrofluoric acid to remove the oxide film, in order to form an ohmic contact layer of the TFT 18, for example, n ⁺ a-Si is rapidly reduced by plasma CVD. It is laminated on the entire surface of the substrate to a thickness of 30 nm. Next, for example, an Al layer (or Al alloy layer) and a refractory metal layer made of Ti or Ti alloy are laminated by sputtering to 100 nm and 80 nm, respectively, to obtain a conductive layer. The conductive layer is used to form the reflective layer 25 functioning as one (intermediate electrode) of a pair of electrodes for forming an auxiliary capacitor (storage capacitor), and the drain electrode and the source electrode of the TFT 18. Cr, Mo, Ta, W, or alloys thereof can also be used for the refractory metal layer.

Next, a photoresist layer is formed on the entire surface of the substrate, the resist is exposed using a third mask, and then the resist layer is patterned by development. Using the patterned resist layer as an etching mask, the conductive layer, the n ⁺ a-Si layer, and the amorphous silicon layer are subjected to dry etching using a chlorine-based gas to obtain a reflective layer as shown in FIG. At the same time, the signal line 12 and the drain electrode, source electrode, ohmic layer, and operating semiconductor layer of the TFT 18 are formed. In this etching process, since the channel protective film functions as an etching stopper, the amorphous silicon layer in the channel portion remains without being etched, and a desired operation semiconductor layer is formed.

Next, as shown in FIG. 14D, for example, a silicon nitride film (SiN) is formed on the entire surface of the substrate with a thickness of about 300 nm by the plasma CVD method to form the protective layer 33.

Next, as shown in FIG. 14E, color filters 34 made of R, G, and B resins are formed by photolithography on R (red), G (green), and B (blue) pixels, respectively. To do. At this time, a color filter 34 of the same color is formed in each column of the plurality of pixels 10 arranged in a matrix.

In this step, first, for example, an acrylic negative photosensitive resin (red resin) containing a red (R) pigment is applied to the entire surface of the substrate to a thickness of, for example, 170 nm using a spin coater, a slit coater, or the like. Next, proximity exposure (proximity exposure) is performed using a fourth mask so that the resin remains in a stripe shape in a predetermined plurality of pixel columns. Next, a color filter 34 made of a red resin is formed by development using an alkaline developer such as KOH (potassium hydroxide). As a result, a red spectral characteristic is imparted to the red pixel, and a light blocking function for preventing external light from entering the TFT 18 is provided.

In the same manner, an acrylic negative photosensitive resin (blue resin) in which a blue (B) pigment is dispersed is applied, and patterned using a fifth mask. A color filter 34 made of resin is formed. As a result, a blue spectral characteristic is imparted to the blue pixel, and a light shielding function for preventing external light from entering the TFT 18 is provided.

Further, an acrylic negative photosensitive resin (green resin) in which a green (G) pigment is dispersed is applied, and patterning is performed using a sixth mask, so that a pixel between the red pixel column and the blue pixel column is formed. A color filter 34 made of green resin is formed in a row. As a result, green spectral characteristics are imparted to the green pixel, and a light blocking function is provided to prevent external light from entering the TFT 18.

In the step of forming the color filter 34, a contact hole for electrically connecting the drain electrode of the TFT 18 to the upper layer is formed in the color filter 34.

Next, as shown in FIG. 15 (f), a transparent insulating resin is applied to the entire surface of the substrate using a spin coater, a slit coater or the like, and heat-treated at a temperature of 140 ° C. or lower. The transparent insulating resin used here is a negative photosensitive acrylic resin. Next, the transparent insulating resin is subjected to proximity exposure using a seventh mask, and developed using an alkali developer such as KOH, whereby the transparent insulating layer 35 is formed.

In this step, a contact hole for electrically connecting the drain electrode of the TFT 18 to the upper layer is formed in the transparent insulating layer 35 on the contact hole of the color filter 34. Here, the protective layer 33 is exposed in the contact hole. Furthermore, contact holes are also formed in at least the terminal formation region and the electrode connection region, and the gate insulating layer 32 or the protective layer 33 is exposed inside the contact hole. Subsequently, dry etching using a fluorine-based gas is performed using the transparent insulating layer 35 as a mask, and the protective layer 33 and the gate insulating layer 32 below the contact hole are removed.

Next, a transparent acrylic resin is applied to the entire surface of the substrate using a spin coater, a slit coater or the like, and heat-treated at a temperature of 140 ° C. or lower. The transparent acrylic resin used is an acrylic resin having negative photosensitivity. The transparent acrylic resin is subjected to proximity exposure through an eighth mask and developed using an alkali developer such as KOH to form a transparent resin layer 36 as shown in FIG. Here, the transparent resin layer 36 is formed on the reflective region 17 or the auxiliary capacitance line 15 in FIG. The transparent resin layer 36 is not formed in the

transmission regions

16a and 16b.

Subsequently, ITO (indium tin oxide), which is a transparent oxide conductive material, is laminated on the entire surface with a thickness of 70 nm by a thin film forming method such as sputtering. Thereafter, a resist mask having a predetermined pattern is formed using a ninth mask, and wet etching using an oxalic acid-based etchant is performed on ITO to obtain a pixel electrode 20 shown in FIG. The

sub pixel electrodes

20 a, 20 b and 20 c included in the pixel electrode 20 are electrically connected to each other by a part of the pixel electrode 20. The sub-pixel electrode 20b included in the pixel electrode 20 is electrically connected to the source electrode of the TFT 18 and the reflective layer (intermediate electrode) 25 through a contact hole. After the pixel electrode 20 is formed, the substrate is subjected to a heat treatment within a range of 150 to 230 ° C., preferably 200 ° C.

Next, a transparent acrylic resin is applied to the entire surface of the substrate using a spin coater, a slit coater, or the like, and heat-treated at a temperature of 140 ° C. or lower. The transparent acrylic resin used is an acrylic resin having negative photosensitivity. Next, proximity exposure is performed on the transparent acrylic resin using a tenth mask, and development is performed using an alkali developer such as KOH, so that protrusions (ribs) 27 shown in FIG. As shown in FIG. 12, the protrusion 27 is formed on the boundary between the adjacent pixels 10 and on the boundary between the transmissive region 16 and the reflective region 17, and is formed so as to surround the

sub-pixel electrodes

20a, 20b, and 20c. Is done.

Next, a method for manufacturing the counter substrate 40 will be described with reference to FIG.

First, ITO, which is a transparent oxide conductive material, is directly laminated on the entire surface of the glass substrate 41, which is a transparent insulating substrate, with a thickness of 100 nm by sputtering or the like. Thereby, the counter electrode 42 made of ITO is formed as shown in FIG.

Next, a transparent acrylic resin is applied to the entire upper surface of the counter electrode 42 using a spin coater, a slit coater, or the like, and heat treatment is performed at a temperature of 140 ° C. or lower. The transparent acrylic resin used is an acrylic resin having negative photosensitivity. Next, proximity exposure is performed on the transparent acrylic resin through the eleventh mask, and development is performed using an alkali developer such as KOH to form protrusions (ribs) 45a and 45c shown in FIG. At this time, the protrusion 45b shown in FIG. 12 is also formed at the same time. The

protrusions

45a, 45b, and 45c are disposed approximately at the centers of the

sub-pixel electrodes

20a, 20b, and 20c, respectively.

The liquid crystal display device 100 thus formed aligns liquid crystal molecules radially and stably in each of the transmission region 16a, the transmission region 16b, and the reflection region 17 by the

protrusions

27, 45a, 45b, and 45c. Therefore, the response speed is fast and display with excellent viewing angle characteristics is possible. In addition, since the unevenness reflecting the shape of the auxiliary capacitance electrode 15c is formed in the reflective layer 25 of the reflective region 17, the reflected light can be irregularly reflected, so that high viewing angle characteristics can be obtained.

However, in manufacturing the liquid crystal display device 100, as described above, a relatively large number of masks such as a total of 11 sheets and a shaping process corresponding to each mask are required.

An object of the present invention is to produce a liquid crystal display device having a high response speed and a good viewing angle characteristic with a relatively small number of steps and with a high production efficiency.

The liquid crystal display device according to the present invention includes a pixel including a reflective region that displays light by reflecting light incident from the display surface side, and a transmissive region that transmits light incident from the side opposite to the display surface. A liquid crystal display device comprising a plurality of TFTs arranged for each of the plurality of pixels, a first transparent layer and a second transparent layer formed on the TFT, and the first transparent layer or the first transparent layer. A TFT substrate having a pixel electrode formed on two transparent layers, a counter substrate having a counter electrode opposite to the pixel electrode, and a liquid crystal layer disposed between the TFT substrate and the counter substrate, The pixel electrode includes a first sub-pixel electrode formed in the reflective region and a second sub-pixel electrode formed in the transmissive region, and the first sub-pixel electrode is the second sub-pixel electrode. It is formed on the surface of the transparent layer on the liquid crystal layer side. The second subpixel electrode is formed on a surface of the first transparent layer on the liquid crystal layer side, and the second transparent layer protrudes to the liquid crystal layer side of the first subpixel electrode, A first protrusion formed to surround the first subpixel electrode and the second subpixel electrode;

In one embodiment, the TFT substrate includes a plurality of scanning lines that supply gate signals to the TFTs and a plurality of signal lines that supply display signals to the TFTs, and each of the plurality of pixels includes the plurality of scanning lines. Arranged between two adjacent lines and two adjacent signal lines, and the first protrusion is located on the two adjacent scanning lines and the two adjacent signal lines, and It is formed in a region between the first subpixel electrode and the second subpixel electrode.

In one embodiment, the first protrusion is formed by overlapping the second transparent layer on the first transparent layer.

An embodiment includes a protective layer formed on the TFT and a color filter layer formed on the protective layer, wherein an opening or a depression is formed in the color filter layer, A part of the first transparent layer is formed in the opening or the depression, and the first protrusion of the second transparent layer is formed on the opening or the depression.

In one embodiment, the height of the surface of the first protrusion on the counter substrate side with respect to the surface of the first subpixel electrode is 0.5 μm or more and 1.0 μm or less.

In one embodiment, a second protrusion reaching the TFT substrate is formed on the surface of the counter electrode in the reflective region, and toward the TFT substrate on the surface of the counter electrode in the transmissive region. A third protrusion that extends is formed.

In one embodiment, the second protrusion and the third protrusion are formed on the centers of the first subpixel electrode and the second subpixel electrode, respectively.

In one embodiment, the second transparent layer in the reflective region includes a fourth protrusion reaching the counter electrode, and the second transparent layer in the transmissive region is formed on the first transparent layer, A fifth protrusion reaching the counter substrate is included.

In one embodiment, the fourth protrusion is formed by forming the second transparent layer on the first transparent layer.

In one embodiment, the fourth protrusion and the fifth protrusion are formed at center positions of the first sub-pixel electrode and the second sub-pixel electrode, respectively.

In one embodiment, the TFT substrate includes a storage capacitor line extending through the reflection region, and a reflective layer disposed between the storage capacitor line and the first subpixel electrode, and the pixel electrode; The reflection layer is electrically connected, and an auxiliary capacitance is formed between the auxiliary capacitance line and the reflection layer.

In one embodiment, an opening or a depression is formed in a portion of the auxiliary capacitance line facing the reflection layer, and an unevenness reflecting the opening or depression of the auxiliary capacitance line is formed in the reflection layer. .

In one embodiment, the transmissive region includes a first transmissive region and a second transmissive region arranged so as to sandwich the reflective region.

In one embodiment, the liquid crystal layer is a vertical alignment type liquid crystal layer including liquid crystal molecules having negative dielectric anisotropy.

The manufacturing method according to the present invention includes a pixel including a reflective region that displays light by reflecting light incident from the display surface side, and a transmissive region that displays light by transmitting light incident from the side opposite to the display surface. A method for manufacturing a plurality of TFT substrates of a liquid crystal display device, comprising: a first step of forming a TFT for each of the plurality of pixels; a second step of forming a first transparent layer after the first step; A third step of forming a second transparent layer after the second step, and a fourth step of forming a pixel electrode on the first transparent layer and the second transparent layer after the third step. In the third step, a first protrusion extending around each of the reflective region and the transmissive region is formed on the second transparent layer, and the fourth step includes forming the second transparent layer in the reflective region. Forming a first sub-pixel electrode on the layer; Forming a second subpixel electrode on the first transparent layer in the transmissive region, and forming the first subpixel electrode and the second subpixel electrode surrounded by the first protrusion. The

An embodiment further includes a step of forming a plurality of scanning lines for supplying a gate signal to the TFT and a step of forming a plurality of signal lines for supplying a display signal to the TFT, and each of the plurality of pixels includes: The plurality of scanning lines are disposed between two adjacent ones of the plurality of scanning lines and two adjacent ones of the plurality of signal lines. In the third step, the first protrusion is formed by the two adjacent scanning lines and the adjacent ones. It is formed on the two matching signal lines and in a region between the reflection region and the transmission region.

In one embodiment, in the third step, the first protrusion is formed by overlapping the second transparent layer on the first transparent layer.

An embodiment further includes a step of forming a protective layer on the TFT, and a step of forming a color filter including an opening or a depression on the protective layer. In the second step, the first step A part of the transparent layer is formed in the opening or the depression, and in the third step, a part of the second transparent layer is formed on the part of the first transparent layer. A first protrusion is formed.

In one embodiment, in the third step, in the second transparent layer, a first central protrusion that protrudes from the first protrusion at a central portion of the reflective region, and the first protrusion at a central portion of the transmissive region. A second central protrusion that protrudes more than the center is formed.

In one embodiment, in the third step, the first central protrusion and the second central protrusion are formed by forming the second transparent layer on the first transparent layer.

In one embodiment, an auxiliary capacitance line extending through the reflection region is formed in the step of forming the scanning line, and a reflective layer is formed on the auxiliary capacitance line in the step of forming the signal line. The

In one embodiment, an opening or a depression is formed in the portion of the auxiliary capacitance line, and an unevenness reflecting the opening or the depression of the auxiliary capacitance line is formed in the reflective layer.

In one embodiment, the TFT substrate is formed using nine or nine or fewer photomasks.

According to the present invention, it is possible to efficiently provide a liquid crystal display device having excellent response speed and viewing angle characteristics.

It is the perspective view which represented typically the structure of the liquid crystal display device 101 of Embodiment 1 by this invention. 3 is a plan view schematically showing a circuit configuration of a TFT substrate 10 in the liquid crystal display device 101 of Embodiment 1. FIG. 3 is a plan view schematically showing the configuration of one pixel of the liquid crystal display device 101. FIG. FIGS. 3A and 3B are cross-sectional views showing configurations of the A-A ′ cross section and the B-B ′ cross section in FIG. 3 of the liquid crystal display device 101, respectively. It is a figure for demonstrating the orientation of the liquid crystal molecule 51 in the liquid crystal layer 50, (a) and (b) are orientations when a voltage is not applied to the liquid crystal layer 50, (c) and (d) are liquid crystals. The orientation when a voltage is applied to the layer 50 is shown. (A) to (h) are cross-sectional views showing a method for manufacturing the TFT substrate 30 in the liquid crystal display device 101. (A) And (b) is sectional drawing showing the manufacturing method of the opposing board | substrate 40 in the liquid crystal display device 101. FIG. FIG. 6 is a plan view schematically showing the configuration of one pixel of the liquid crystal display device 102 of Embodiment 2. FIGS. 8A and 8B are cross-sectional views showing configurations of the A-A ′ cross section and the B-B ′ cross section in FIG. 8 of the liquid crystal display device 102, respectively. It is a figure for demonstrating the orientation of the liquid crystal molecule 51 in the liquid crystal layer 50, (a) and (b) are orientations when a voltage is not applied to the liquid crystal layer 50, (c) and (d) are liquid crystals. The orientation when a voltage is applied to the layer 50 is shown. (A) to (c) are cross-sectional views showing the latter half of the manufacturing method of the TFT substrate 30 in the liquid crystal display device 102. It is the top view which represented typically the structure of one pixel in the liquid crystal display device 100 which is an example of a reflective transmissive liquid crystal display device. (A) and (b) are diagrams showing configurations of the A-A ′ section and the B-B ′ section in FIG. 12 of the liquid crystal display device 100, respectively. FIGS. 7A to 7E are cross-sectional views illustrating the first half of the method for manufacturing the TFT substrate 30 in the liquid crystal display device 100. FIGS. (F) to (i) are cross-sectional views showing the latter half of the manufacturing method of the TFT substrate 30 in the liquid crystal display device 100. FIG. (A) And (b) is sectional drawing showing the manufacturing method of the opposing board | substrate 40 in the liquid crystal display device 100. FIG.

Hereinafter, the configuration of a reflection-transmission type liquid crystal display device according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below. In the following description, the same reference numerals are assigned to components corresponding to the components of the liquid crystal display device 100 described above.

(Embodiment 1)
FIG. 1 schematically shows the structure of the liquid crystal display device 101 according to the first embodiment of the present invention, and FIG. 2 schematically shows the circuit configuration of the TFT substrate 30 of the liquid crystal display device 101.

As shown in FIG. 1, the liquid crystal display device 101 includes a TFT substrate 30 and a counter substrate 40 facing each other with a liquid crystal layer interposed therebetween, and polarizing plates 66 attached to the outer surfaces of the TFT substrate 30 and the counter substrate 40, respectively. 67 and a backlight unit 68 for emitting display light.

As shown in FIG. 2, a plurality of scanning lines (gate bus lines) 14 and a plurality of signal lines (data bus lines) 12 are disposed on the TFT substrate 30 so as to be orthogonal to each other. A TFT 18 is formed for each pixel 10 in the vicinity of the intersection between the pixel line 10 and the signal line 12. Here, the pixel 10 is defined as a region delimited by a center line between two adjacent scanning lines 14 and two adjacent signal lines 12. Each pixel 10 is provided with a pixel electrode 20 made of ITO and electrically connected to the source electrode of the TFT 18. A storage capacitor line 15 extends in parallel with the scanning line 14 between two adjacent scanning lines 14.

As shown in FIG. 1, the scanning line 14 and the signal line 12 are connected to a scanning line driving circuit 61 and a signal line driving circuit 62, respectively. The scanning line 14 is supplied with a scanning signal for switching on / off of the TFT 18 from the scanning line driving circuit 61 in accordance with the control by the control circuit 63, and the signal line 12 is driven by the signal line in accordance with the control by the control circuit 63. A display signal (voltage applied to the pixel electrode 20) is supplied from the circuit 62.

3 is a plan view schematically showing the configuration of one pixel of the liquid crystal display device 101. FIGS. 4A and 4B are cross-sectional views taken along line AA ′ in FIG. FIG. 4 is a cross-sectional view illustrating a configuration of a cross section and a BB ′ cross section.

The pixel 10 of the liquid crystal display device 101 includes two transmissive regions 16 (the upper transmissive region is 16a and the lower transmissive region is 16b) and one reflective region 17 sandwiched between the two

transmissive regions

16a and 16b. And have. The pixel electrode 20 of the pixel 10 includes a sub-pixel electrode 20a (corresponding to the second sub-pixel electrode) in the transmissive region 16a, a sub-pixel electrode 20b (corresponding to the second sub-pixel electrode) in the transmissive region 16b, and a reflective region 17 A sub pixel electrode 20c (corresponding to the first sub pixel electrode). The sub pixel electrode 20a and the sub pixel electrode 20c, and the sub pixel electrode 20b and the sub pixel electrode 20c are connected to each other by a part of the pixel electrode 20.

4A is a cross-sectional view of the reflective region 17, and FIG. 4B is a cross-sectional view of the transmissive region 16a. As shown in FIG. 4, the liquid crystal display device 101 includes a TFT substrate 30, a counter substrate 40, and a liquid crystal layer 50 disposed between the TFT substrate 30 and the counter substrate 40. The liquid crystal layer 50 is a vertical alignment type liquid crystal layer including liquid crystal molecules having negative dielectric anisotropy.

The TFT substrate 30 includes a glass substrate 31, a gate insulating layer 32 formed on the glass substrate 31, a protective layer 33 formed on the gate insulating layer 32, and a color filter (CF ) 34 (corresponding to the color filter layer), and a transparent insulating layer (JAS) 35 (corresponding to the first transparent layer) formed on the color filter 34. A transparent resin layer 36 (corresponding to the second transparent layer) is formed on the color filter 34 in the reflective region 17, and the sub-pixel electrode 20 c is formed on the transparent resin layer 36. The transparent resin layer 36 is not formed under the

sub-pixel electrodes

20a and 20b in the

transmissive regions

16a and 16b, and the

sub-pixel electrodes

20a and 20b are formed on the transparent insulating layer 35.

The transparent insulating layer 35 and the transparent resin layer 36 are provided between the

sub-pixel electrodes

20a and 20c, the region between the

sub-pixel electrodes

20c and 20b, and the pixel electrode 20 of two adjacent pixels 10, that is, a transmission region. It is also formed at a boundary portion between 16a and the reflection region 17, a boundary portion between the reflection region 17 and the transmission region 16b, and a boundary portion between two adjacent pixels 10. Since the transparent insulating layer 35 and the transparent resin layer 36 overlap with each other, the transparent resin layer 36 has a protrusion (rib) 77 (projected from the sub-pixel electrode 20c by a distance d1 at the boundary portion) by a distance d1. Corresponding to the first protrusion). The value of d1 is not less than 0.5 μm and not more than 1.0 μm, for example. As shown in FIG. 3, the protrusion 77 extends around the

transmission regions

16a and 16b and the reflection region 17 so as to surround each of the

sub-pixel electrodes

20a, 20b, and 20c. An opening or a depression of the color filter 34 is formed under the protrusion 77.

The TFT 18 shown in FIG. 3 is also formed between the gate insulating layer 32 and the protective layer 33. The TFT 18 has an operating semiconductor layer made of, for example, amorphous silicon (a-Si) constituting the channel of the TFT 18 and an ohmic contact layer that is an n ⁺ -Si layer. The ohmic contact layer is connected to the source electrode and the drain electrode, and the source electrode is connected to the upper subpixel electrode through a contact hole formed by opening the protective layer 33, the color filter 34, and the transparent insulating layer 35. 20b is electrically connected. The source electrode is also electrically connected to the reflective layer 25 in the reflective region 17, and the reflective layer 25 is a contact hole formed by opening the protective layer 33, the color filter layer 34, and the transparent resin layer 36. Is electrically connected to the upper sub-pixel electrode 20c.

The counter substrate 40 includes a glass substrate 41, a counter electrode 42 formed on the liquid crystal layer 50 side of the glass substrate 41, and protrusions (ribs) 45 formed at three locations on the surface of the counter electrode 42 on the liquid crystal layer 50 side. (45a, 45b, and 45c). The protrusions 45a (corresponding to the third protrusions), 45b (corresponding to the third protrusions), and 45c (corresponding to the second protrusions) are formed above the center positions of the

sub-pixel electrodes

20a, 20b, and 20c, respectively. .

The cell gap (distance between the sub-pixel electrode 20c and the counter electrode 42 or the thickness of the liquid crystal layer 50 sandwiched between both electrodes) d2 in the reflective region 17 is, for example, 1.7 μm, and the

transmissive regions

16a and 16b The cell gap d3 (distance between the

sub-pixel electrodes

20a and 20b and the counter electrode 42, or the thickness of the liquid crystal layer 50 sandwiched between both electrodes) d3 is, for example, 3.4 μm. Thus, the cell gap between the

transmissive regions

16 a and 16 b is twice as thick as the cell gap of the reflective region 17. The cell gap of the

transmissive regions

16a and 16b is preferably in the range of 1.7 to 2.3 times the cell gap of the reflective region 17. The distance (distance in the vertical direction of the substrate surface) d4 from the surface of the

subpixel electrodes

20a and 20b on the liquid crystal layer 50 side to the upper surface of the projection 77 is 2.2 μm or more and 2.7 μm or less.

The

protrusions

45a, 45b, and 45c, together with the protrusion 77 of the TFT substrate 30, control the alignment of the liquid crystal molecules in the transmissive region 16a, the transmissive region 16b, and the reflective region 17 in a radial manner around the

protrusions

FIG. 5 is a diagram for explaining the alignment of the liquid crystal molecules 51 in the liquid crystal layer 50. 5A and 5B show the orientation of the liquid crystal molecules 51 in the reflective region 17 and the transmissive region 16a when no voltage is applied between the pixel electrode 20 and the counter electrode 42, respectively. 5 (c) and 5 (d) show the orientation of the liquid crystal molecules 51 in the reflective region 17 and the transmissive region 16a when a voltage is applied between the pixel electrode 20 and the counter electrode 42, respectively.

As shown in FIGS. 5A and 5B, when no voltage is applied, most liquid crystal molecules are formed on the surface of the pixel electrode 20 and the counter electrode 42 on the liquid crystal layer 50 side. Alignment is almost perpendicular to the substrate surface by the action of the non-alignment film. However, since the alignment film is also formed on the surface of the

protrusions

77 and 45 on the liquid crystal layer 50 side, the liquid crystal molecules 51 near the

protrusions

77 and 45 tend to align perpendicularly to these surfaces. Therefore, the liquid crystal molecules 51 in the vicinity of the

protrusions

77 and 45 are oriented obliquely with respect to the substrate surface and toward the inside of the reflective region 17 and the

transmissive regions

16a and 16b, respectively. Such tilted orientation of the liquid crystal molecules 51 when no voltage is applied is referred to as pretilt.

As shown in FIGS. 5C and 5D, when the TFT 18 is turned on and a voltage is applied between the electrodes from the signal line 12, the liquid crystal molecules 51 are parallel to the equipotential surface, that is, the substrate. Inclined orientation in a direction almost parallel to the surface. At this time, the liquid crystal molecules 51 are dragged in the alignment direction of the liquid crystal molecules 51 that have been pretilted when no voltage is applied. In each of the reflective region 17, the transmissive region 16a, and the transmissive region 16b, the liquid crystal molecules 51 are approximately at the centers (

projections

45a, 45b and 45c, which are radially oriented so as to go to the approximate center of each of 45b and 45c, or from the center to the outside of the region.

In this way, the liquid crystal molecules 51 can be more isotropically aligned in a plane parallel to the substrate surface in each of the reflective region 17, the transmissive region 16a, and the transmissive region 16b. improves. Further, since the orientation direction of the liquid crystal molecules 51 at the time of voltage application can be defined by the pretilt at the time of voltage application, the response speed in display is improved.

Next, a method for manufacturing the liquid crystal display device 101 will be described with reference to FIGS. 6A to 6H are cross-sectional views showing a manufacturing method of the TFT substrate 30 of the liquid crystal display device 101. FIGS. 7A and 7B are cross-sectional views of the counter substrate 40 of the liquid crystal display device 101. FIG. It is sectional drawing showing this manufacturing method. In each figure, a cross section of the reflection region 17 (corresponding to the A-A 'cross section in FIG. 3) is shown on the left side, and a cross section of the transmission region 16a (corresponding to the B-B' cross section in FIG. 3) is shown on the right side.

In manufacturing the TFT substrate 30, first, Al (aluminum) or an Al alloy is laminated on the entire upper surface of the glass substrate 31 which is a transparent insulating substrate to a thickness of, for example, 130 nm by sputtering. If necessary, a protective film such as SiOx may be formed on the upper surface of the glass substrate 31 before lamination. Next, Ti (titanium) or a titanium alloy is laminated to a thickness of, for example, 70 nm on the laminated Al or the like by sputtering. Thereby, a metal layer having a thickness of about 200 nm is formed. Here, instead of Ti, Cr (chromium), Mo (molybdenum), Ta (tantalum), W (tungsten), or an alloy of these metals can be used. Further, instead of Al, a material containing one or more of Nd (neodymium), Si (silicon), Cu (copper), Ti, W, Ta, and Sc may be used.

Thereafter, a resist layer is formed on the metal layer, exposed through a first mask (photomask or reticle, hereinafter simply referred to as a mask) to form a resist mask, and dry etching using a chlorine-based gas. The metal layer is patterned to form the auxiliary capacitance electrode 15c as shown in FIG. At this time, the scanning line 14, the auxiliary capacitance line 15, and the gate electrode of the TFT 18 are also formed simultaneously. At this time, an opening or a depression is formed in the auxiliary capacitance electrode 15c.

Next, as shown in FIG. 6B, for example, a silicon nitride film (SiN) is formed on the entire surface of the substrate to a thickness of about 400 nm by plasma CVD to obtain the gate insulating layer 32. Next, in order to form an operating semiconductor layer of the TFT 18, an amorphous silicon (a-Si) layer (not shown), for example, is laminated on the entire surface of the substrate to a thickness of about 30 nm by plasma CVD. Further, in order to form a channel protective film (etching stopper) of the TFT 18, for example, a silicon nitride film (SiN) (not shown) is formed with a film thickness of about 150 nm on the entire surface of the substrate by plasma CVD.

The resist pattern is further exposed from the forward direction (on the side opposite to the glass substrate 31) through the second mask to leave the resist layer only on the region where the channel protective film is to be formed. . Thereafter, by using this resist layer as an etching mask, the silicon nitride film is dry-etched using a fluorine-based gas to form a channel protective film. As shown in FIG. 6B, the channel protective film does not remain on the auxiliary capacitance electrode 15c.

Next, as shown in FIG. 6D, for example, a silicon nitride film (SiN) is formed on the entire surface of the substrate with a thickness of about 300 nm by the plasma CVD method to form the protective layer 33.

Next, as shown in FIG. 6E, color filters 34 made of R, G, and B resins are formed by photolithography on R (red), G (green), and B (blue) pixels, respectively. To do. At this time, the color filter 34 of the same color is formed in each column (pixel column aligned in the vertical direction in FIG. 2) in the plurality of pixels 10 arranged on the matrix.

Next, a transparent insulating resin is applied to the entire surface of the substrate using a spin coater, a slit coater, or the like, and heat-treated at a temperature of 140 ° C. or lower. The transparent insulating resin used here is a negative photosensitive acrylic resin. Next, the transparent insulating resin is subjected to proximity exposure using a seventh mask and developed using an alkali developer such as KOH, whereby a transparent insulating layer 35 is formed as shown in FIG.

The transparent insulating layer 35 is a region on the color filter 34 in the transmissive region 16 and a region where the color filter 34 is not formed between the transmissive region 16 and the reflective region (the depression of the color filter 34 may be formed). However, it is not formed on the color filter 34 in the reflective region 17.

In this step, a contact hole for electrically connecting the drain electrode of the TFT 18 to the upper layer is formed in the transparent insulating layer 35 on the contact hole of the color filter 34. The protective layer 33 is exposed in the contact hole. Furthermore, contact holes are also formed at least in the terminal formation region and the electrode connection region, and the gate insulating layer 32 or the protective layer 33 is exposed inside. Subsequently, dry etching using a fluorine-based gas is performed using the transparent insulating layer 35 as a mask, and the protective layer 33 and the gate insulating layer 32 below the contact hole are removed.

Next, a transparent acrylic resin is applied to the entire surface of the substrate using a spin coater, a slit coater or the like, and heat-treated at a temperature of 140 ° C. or lower. The transparent acrylic resin used is an acrylic resin having negative photosensitivity. The transparent acrylic resin is subjected to proximity exposure through an eighth mask and developed using an alkali developer such as KOH to form a transparent resin layer 36 as shown in FIG.

Here, the transparent resin layer 36 is formed on the reflective region 17 or the auxiliary capacitance line 15 in FIG. The transparent resin layer 36 is formed on the color filter 34 in the reflective region 17 and on the region where the color filter 34 between the transmissive region 16 and the reflective region is not formed, but the

transmissive regions

16a and 16b. It is not formed on the color filter 34. In the step of forming the transparent resin layer 36, the projection 77 of the transparent resin layer 36 is formed by forming the transparent resin layer 36 on the transparent insulating layer 35.

Subsequently, ITO (indium tin oxide), which is a transparent oxide conductive material, is laminated on the entire surface with a thickness of 70 nm by a thin film forming method such as sputtering. Thereafter, a resist mask having a predetermined pattern is formed using a ninth mask, and wet etching using an oxalic acid-based etchant is performed on ITO to obtain a pixel electrode 20 shown in FIG. After the pixel electrode 20 is formed, the substrate is subjected to a heat treatment within a range of 150 to 230 ° C., preferably 200 ° C.

The

sub-pixel electrodes

20a, 20b, and 20c included in the pixel electrode 20 are electrically connected to each other by a part of the pixel electrode 20. The sub-pixel electrode 20b is electrically connected to the source electrode of the TFT 18 and the reflective layer (intermediate electrode) 25 through a contact hole. The pixel electrode 20 is not formed on the protrusion 77. The protrusion 77 surrounds the

sub-pixel electrodes

20a, 20b, and 20c on the boundary between the adjacent pixels 10 (the region between the two adjacent pixel electrodes 20) and on the boundary between the transmissive region 16 and the reflective region 17. It is formed as follows.

First, ITO, which is a transparent oxide conductive material, is directly laminated on the entire surface of the glass substrate 41, which is a transparent insulating substrate, with a thickness of 100 nm by sputtering or the like. Thereby, as shown in FIG. 7A, the counter electrode 42 made of ITO is formed.

Next, a transparent acrylic resin is applied to the entire upper surface of the counter electrode 42 using a spin coater, a slit coater, or the like, and heat treatment is performed at a temperature of 140 ° C. or lower. The transparent acrylic resin used is an acrylic resin having negative photosensitivity. Next, proximity exposure is performed on the transparent acrylic resin through the tenth mask, and development is performed using an alkaline developer such as KOH to form protrusions (ribs) 45a and 45c shown in FIG. 7B. At this time, the protrusion 45b shown in FIG. 3 is also formed at the same time. The

protrusions

45a, 45b, and 45c are disposed approximately at the centers of the

sub-pixel electrodes

20a, 20b, and 20c, respectively.

The liquid crystal display device 101 formed in this manner stably aligns liquid crystal molecules radially in each of the transmission region 16a, the transmission region 16b, and the reflection region 17 by the

protrusions

77, 45a, 45b, and 45c. Therefore, the response speed is fast and display with excellent viewing angle characteristics is possible. In addition, since the unevenness reflecting the shape of the auxiliary capacitance electrode 15c is formed in the reflective layer 25 of the reflective region 17, the reflected light can be irregularly reflected, so that high viewing angle characteristics can be obtained.

Further, in the manufacturing process of the liquid crystal display device 101, only one less mask (10 in this embodiment) than the liquid crystal display device 100 shown in FIG. 12 is required, so that the manufacturing process can be made more efficient or simple. Can be

(Embodiment 2)
Next, a liquid crystal display device 102 according to a second embodiment of the present invention will be described. Since the basic configuration of the liquid crystal display device 102 is the same as that of the first embodiment shown in FIGS. 1 and 2, the description of the basic configuration is omitted.

FIG. 8 is a plan view schematically showing the configuration of one pixel of the liquid crystal display device 102. FIGS. 9A and 9B are respectively AA ′ in FIG. FIG. 4 is a cross-sectional view illustrating a configuration of a cross section and a BB ′ cross section.

The pixel 10 of the liquid crystal display device 102 basically has the same configuration as the liquid crystal display device 101 shown in FIG. However, the protrusion 77 formed on the counter substrate 40 in the liquid crystal display device 101 does not exist on the liquid crystal display device 102, and has a protrusion 79 formed on the TFT substrate 30 instead. Therefore, hereinafter, the description will focus on the configuration of the projection 79 and the portion related to the projection 79, and much of the description of the same configuration portion as the liquid crystal display device 101 will be omitted.

As shown in FIGS. 8 and 9, the projection 79 includes projections 79a (corresponding to the fifth projection and the second central projection) 79b formed at the center of each of the two

transmission regions

16a and 16b and the reflection region 17. (Corresponding to the fifth protrusion and the second central protrusion) and 79c (corresponding to the fourth protrusion and the first central protrusion). The

protrusions

79a, 79b, and 79c are formed as part of the transparent resin layer 36 so as to reach the counter electrode 42.

The TFT substrate 30 includes a transparent insulating layer 35 formed on the protective layer 33 and the color filter 34, and the transparent insulating layer 35 includes a portion other than the color filter 34 on the reflective region 17 and the reflective region 17. Is formed in the central portion (the portion above the color filter 34 below the protrusion 79c). The transparent insulating layer 35 formed in the central portion of the reflective region 17 is referred to as a transparent insulating layer 35c.

A transparent resin layer 36 is formed on the color filter 34 (including the transparent insulating layer 35 c) in the reflective region 17, and a sub-pixel electrode 20 c is formed on the transparent resin layer 36. The transparent resin layer 36 is not formed under the

sub-pixel electrodes

20a and 20b in the

transmissive regions

16a and 16b, and the

sub-pixel electrodes

20a and 20b are formed on the transparent insulating layer 35. The transparent resin layer 36 is also formed at the center of the

transmissive regions

16a and 16b, forming

projections

79a and 79b. Openings are formed in the central portions of the

subpixel electrodes

20a and 20b, and the

protrusions

79a and 79b are formed on these openings, that is, on the transparent insulating layer 35 in the central portions of the

transmission regions

16a and 16b.

sub-pixel electrodes

20a and 20c, the region between the

sub-pixel electrodes

20c and 20b, and the pixel electrode 20 of two adjacent pixels 10, that is, a transmission region. It is also formed at a boundary portion between 16a and the reflection region 17, a boundary portion between the reflection region 17 and the transmission region 16b, and a boundary portion between two adjacent pixels 10. Since the transparent insulating layer 35 and the transparent resin layer 36 overlap each other, the transparent resin layer 36 has a protrusion (rib) 77 protruding at a distance d1 from the sub pixel electrode 20c toward the liquid crystal layer 50 at the boundary portion. Including. The value of d1 is not less than 0.5 μm and not more than 1.0 μm, for example. As shown in FIG. 8, the protrusion 77 extends around the

transmission regions

16a and 16b and the reflection region 17 so as to surround each of the

sub-pixel electrodes

20a, 20b, and 20c.

The counter substrate 40 includes a glass substrate 41 and a counter electrode 42 formed on the liquid crystal layer 50 side of the glass substrate 41. The protrusion 45 of the first embodiment is not formed on the surface of the counter electrode on the liquid crystal layer 50 side.

The cell gap d2 in the reflective region 17 is, for example, 1.7 μm, and the cell gap d3 in the

transmissive regions

16a and 16b is, for example, 3.4 μm. The distance d4 from the surface on the liquid crystal layer 50 side of the

sub-pixel electrodes

20a and 20b to the upper surface of the protrusion 77 is 2.2 μm or more and 2.7 μm or less.

The

protrusions

79a, 79b, and 79c together with the protrusion 77 function as an alignment control means for radially aligning the liquid crystal molecules 51 in the transmission region 16a, the transmission region 16b, and the reflection region 17 with the

protrusions

79a, 79b, and 79c as the center. . Further, the

projections

79a, 79b, and 79c also serve as spacers for keeping the cell gap constant.

FIG. 10 is a diagram for explaining the alignment of the liquid crystal molecules 51 in the liquid crystal layer 50. FIGS. 10A and 10B show the orientation of the liquid crystal molecules 51 in the reflective region 17 and the transmissive region 16a when no voltage is applied between the pixel electrode 20 and the counter electrode 42, respectively. 10 (c) and 10 (d) represent the orientation of the liquid crystal molecules 51 in the reflective region 17 and the transmissive region 16a when a voltage is applied between the pixel electrode 20 and the counter electrode 42, respectively.

As shown in FIGS. 10A and 10B, when no voltage is applied, most of the liquid crystal molecules 51 are formed on the surface of the pixel electrode 20 and the counter electrode 42 on the liquid crystal layer 50 side. The alignment film is oriented substantially perpendicular to the substrate surface by the action of the alignment film. However, since the alignment film is also formed on the surface of the protrusion 77 on the liquid crystal layer 50 side and also on the side surface of the protrusion 79, the liquid crystal molecules 51 near the

protrusion

77 and 79 are perpendicular to the surface of the

protrusion

77 and 79. Try to orient. Therefore, the liquid crystal molecules 51 in the vicinity of the

protrusions

77 and 79 are oriented obliquely with respect to the substrate surface toward the inside of the reflective region 17 and the

transmissive regions

16a and 16b. Such tilted orientation of the liquid crystal molecules 51 when no voltage is applied is referred to as pretilt.

As shown in FIGS. 10C and 10D, when the TFT 18 is turned on and a voltage is applied from the signal line 12 between the electrodes, the liquid crystal molecules 51 are parallel to the equipotential surface, that is, the substrate. Inclined orientation in a direction almost parallel to the plane At this time, the liquid crystal molecules 51 are dragged in the alignment direction of the liquid crystal molecules 51 that have been pretilted when no voltage is applied. In each of the reflective region 17, the transmissive region 16a, and the transmissive region 16b, the liquid crystal molecules 51 are approximately at the centers (

projections

79a, 79b and 79c (approximately the center of each) or radially from the center toward the outside of the region.

Next, a method for manufacturing the liquid crystal display device 102 will be described with reference to FIG. FIGS. 11A to 11C are cross-sectional views showing a manufacturing method of the TFT substrate 30 of the liquid crystal display device 102, and steps (f) to (h) of FIG. 6 in the manufacturing method of the first embodiment. It is a figure corresponding to. In FIG. 11, the cross section of the reflection region 17 (corresponding to the A-A 'cross section in FIG. 8) is shown on the left side, and the cross section of the transmission region 16a (corresponding to the B-B' cross section in FIG. 8) is shown on the right side.

Since the first half of the manufacturing process of the TFT substrate 30 of the liquid crystal display device 102 (the process corresponding to (a) to (e) of FIG. 6) is the same as that described in the first embodiment, the description will be given here. Omitted. Further, the manufacturing process of the counter substrate 40 is the same as that described in the first embodiment with reference to FIG. 7A (a manufacturing method excluding the process of forming the protrusions 45), and thus the description thereof is omitted.

In the manufacturing process of the liquid crystal display device 102, after the color filter 34 of the TFT substrate 30 is formed, a transparent insulating resin is applied to the entire surface of the substrate using a spin coater, a slit coater or the like, and is heated at a temperature of 140 ° C. or lower. . The transparent insulating resin used here is a negative photosensitive acrylic resin. Next, the transparent insulating resin is subjected to proximity exposure using a seventh mask and developed using an alkali developer such as KOH, whereby a transparent insulating layer 35 is formed as shown in FIG.

The transparent insulating layer 35 is formed on the color filter 34 in the transmissive region 16, on the region where the color filter 34 between the transmissive region 16 and the reflective region 17 is not formed, and on the center of the reflective region 17. Although it is formed, it is not formed on the reflective region 17 other than the central portion of the color filter 34.

Here, the transparent resin layer 36 is formed on the reflective region 17 or the auxiliary capacitance line 15 in FIG. The transparent resin layer 36 is formed on the color filter 34 in the reflective region 17, on the region where the color filter 34 between the transmissive region 16 and the reflective region 17 is not formed, and in the center of the

transmissive regions

16 a and 16 b. Although formed, it is not formed on the color filter 34 other than the central part of the

transmission regions

16a and 16b. By forming the transparent resin layer 36 on the transparent insulating layer 35, the

projections

77 and 79c of the transparent resin layer 36 are formed. Further,

projections

79a and 79b are formed by the transparent resin layer 36 formed at the center of the

transmission regions

16a and 16b.

Subsequently, ITO, which is a transparent oxide conductive material, is laminated with a thickness of 70 nm on the entire surface of the substrate by a thin film formation method such as sputtering. Thereafter, a resist mask having a predetermined pattern is formed using a ninth mask, and wet etching using an oxalic acid-based etchant is performed on ITO to obtain a pixel electrode 20 shown in FIG. After the pixel electrode 20 is formed, the substrate is subjected to a heat treatment within a range of 150 to 230 ° C., preferably 200 ° C.

The

sub-pixel electrodes

20a, 20b, and 20c included in the pixel electrode 20 are electrically connected to each other by a part of the pixel electrode 20. The sub-pixel electrode 20b is electrically connected to the source electrode of the TFT 18 and the reflective layer (intermediate electrode) 25 through a contact hole. The pixel electrode 20 is not formed on the

protrusions

77, 79a, 79b, and 79c. The protrusion 77 surrounds the

sub-pixel electrodes

20a, 20b, and 20c on the boundary between the adjacent pixels 10 (the region between the two adjacent pixel electrodes 20) and on the boundary between the transmissive region 16 and the reflective region 17. Formed as follows.

The liquid crystal display device 102 thus formed aligns liquid crystal molecules radially and stably in each of the transmission region 16a, the transmission region 16b, and the reflection region 17 by the

projections

77, 79a, 79b, and 79c. Therefore, the response speed is fast and display with excellent viewing angle characteristics is possible. In addition, since the unevenness reflecting the shape of the auxiliary capacitance electrode 15c is formed in the reflective layer 25 of the reflective region 17, the reflected light can be irregularly reflected, so that high viewing angle characteristics can be obtained.

Further, in the manufacturing process of the liquid crystal display device 102, only a smaller number of masks (9 in this embodiment) than the liquid crystal display device 100 shown in FIG. 12 are required, so that the manufacturing process can be made more efficient or simplified. be able to.

According to the present invention, the first protrusion (corresponding to the protrusion 77) surrounds the first subpixel electrode (corresponding to the subpixel electrode 20c) and the second subpixel electrode (corresponding to the

subpixel electrode

20a or 20b). Since it is formed, the alignment of the liquid crystal can be regulated by the first protrusion, and it is possible to provide a display with a high response speed and excellent viewing angle characteristics.

In addition, since the first protrusion is formed as a part of the second transparent layer (corresponding to the transparent resin layer 36), a separate process for forming the first protrusion is not required. Therefore, a liquid crystal display device having excellent response speed and viewing angle characteristics can be manufactured with high manufacturing efficiency.

Further, since the first protrusion is obtained by forming a part of the second transparent layer on the first transparent layer (corresponding to the transparent insulating layer 35), a special mask is used only for forming the first protrusion. Is not required. Therefore, it is possible to improve the manufacturing efficiency of a liquid crystal display device having excellent response speed and viewing angle characteristics.

Since the first protrusion is formed by forming a part of the second transparent layer on the first transparent layer formed in the opening or depression of the color filter layer (corresponding to the color filter 34), The first protrusion having an appropriate height can be obtained with high manufacturing efficiency without using a special mask.

Also, the second protrusion (corresponding to the protrusion 45c), the third protrusion (corresponding to the

protrusion

45a or 45b), the fourth protrusion (corresponding to the protrusion 79c), the fifth protrusion (corresponding to the

protrusion

79a or 79b), the first central protrusion Since the orientation of the liquid crystal molecules can be controlled by (corresponding to the protrusion 79c) and the second central protrusion (corresponding to the

protrusion

79a or 79b), display with excellent response speed and viewing angle characteristics is possible.

In addition, since the fourth protrusion, the fifth protrusion, the first center protrusion, and the second center protrusion are obtained by forming a part of the second transparent layer on the first transparent layer, these protrusions are formed. No special mask is needed just to do that. Therefore, the manufacturing efficiency of a liquid crystal display device with excellent response speed and viewing angle characteristics is improved.

The present invention is suitably used for various types of liquid crystal display devices having a TFT substrate.

10 pixel 12 signal line 14 scanning line 15 auxiliary capacitance line 15c

auxiliary capacitance electrode

16, 16a, 16b transmission region 17 reflection region 18 TFT
20

Pixel electrode

20a, 20b, 20c Sub pixel electrode 25 Reflective layer (intermediate electrode)
27 Protrusion (rib)
30 TFT substrate 31 Glass substrate 32 Gate insulating layer 33 Protective layer 34 Color filter 35 Transparent insulating layer (JAS)
36 Transparent resin layer 40 Counter substrate 41 Glass substrate 42

Counter electrode

45, 45a, 45b, 45c Projection (rib)
50 liquid crystal layer 51 liquid crystal molecule 61 scanning line drive circuit 62 signal line drive circuit 63

control circuit

66, 67 polarizing plate 68

backlight unit

77, 79 protrusion (rib)
100, 101, 102 Liquid crystal display device

Claims

A liquid crystal display device comprising a plurality of pixels each including a reflective region for displaying light by reflecting light incident from a display surface side and a transmissive region for transmitting light incident from a side opposite to the display surface There,
TFTs arranged for each of the plurality of pixels, first and second transparent layers formed on the TFTs, and pixel electrodes formed on the first transparent layer or the second transparent layer TFT substrate with
A counter substrate provided with a counter electrode facing the pixel electrode, and a liquid crystal layer disposed between the TFT substrate and the counter substrate,
The pixel electrode includes a first sub-pixel electrode formed in the reflective region and a second sub-pixel electrode formed in the transmissive region;
The first subpixel electrode is formed on a surface of the second transparent layer on the liquid crystal layer side;
The second subpixel electrode is formed on the liquid crystal layer side surface of the first transparent layer;
The liquid crystal display, wherein the second transparent layer includes a first protrusion that protrudes closer to the liquid crystal layer than the first subpixel electrode and is formed to surround the first subpixel electrode and the second subpixel electrode. apparatus.
The TFT substrate includes a plurality of scanning lines for supplying gate signals to the TFTs and a plurality of signal lines for supplying display signals to the TFTs,
Each of the plurality of pixels is disposed between two adjacent ones of the plurality of scanning lines and two adjacent ones of the plurality of signal lines;
The first protrusion is formed on the two adjacent scanning lines and the two adjacent signal lines and in a region between the first subpixel electrode and the second subpixel electrode. Item 2. A liquid crystal display device according to item 1.
The liquid crystal display device according to claim 1 or 2, wherein the first protrusion is formed by overlapping the second transparent layer on the first transparent layer.
A protective layer formed on the TFT, and a color filter layer formed on the protective layer;
An opening or a depression is formed in the color filter layer,
A portion of the first transparent layer is formed in the opening or indentation;
4. The liquid crystal display device according to claim 1, wherein the first protrusion of the second transparent layer is formed on the opening or the depression. 5.
3. The liquid crystal display device according to claim 1, wherein a height of a surface of the first protrusion on the counter substrate side with respect to a surface of the first subpixel electrode is 0.5 μm or more and 1.0 μm or less. .
A second protrusion reaching the TFT substrate is formed on the surface of the counter electrode in the reflective region,
6. The liquid crystal display device according to claim 1, wherein a third protrusion extending toward the TFT substrate is formed on a surface of the counter electrode in the transmissive region.
The liquid crystal display device according to claim 6, wherein the second protrusion and the third protrusion are formed on the centers of the first subpixel electrode and the second subpixel electrode, respectively.
The second transparent layer in the reflective region includes a fourth protrusion reaching the counter electrode;
6. The liquid crystal display device according to claim 1, wherein the second transparent layer in the transmission region includes a fifth protrusion formed on the first transparent layer and reaching the counter substrate.
The liquid crystal display device according to claim 8, wherein the fourth protrusion is formed by forming the second transparent layer on the first transparent layer.
10. The liquid crystal display device according to claim 8, wherein the fourth protrusion and the fifth protrusion are formed at center positions of the first subpixel electrode and the second subpixel electrode, respectively.
The TFT substrate includes a storage capacitor line extending through the reflection region, and a reflective layer disposed between the storage capacitor line and the first subpixel electrode,
The pixel electrode and the reflective layer are electrically connected;
The liquid crystal display device according to claim 1, wherein an auxiliary capacitance is formed between the auxiliary capacitance line and the reflective layer.
An opening or a depression is formed in the portion of the auxiliary capacitance line facing the reflective layer,
The liquid crystal display device according to claim 11, wherein unevenness reflecting the opening or depression of the auxiliary capacitance line is formed in the reflective layer.
The liquid crystal display device according to claim 1, wherein the transmissive region includes a first transmissive region and a second transmissive region arranged so as to sandwich the reflective region.
14. The liquid crystal display device according to claim 1, wherein the liquid crystal layer is a vertical alignment type liquid crystal layer containing liquid crystal molecules having negative dielectric anisotropy.
A liquid crystal display device having a plurality of pixels each including a reflective region that displays light by reflecting light incident from the display surface side and a transmissive region that transmits light incident from the side opposite to the display surface A manufacturing method of a TFT substrate,
A first step of forming a TFT for each of the plurality of pixels;
A second step of forming a first transparent layer after the first step;
A third step of forming a second transparent layer after the second step;
A fourth step of forming a pixel electrode on the first transparent layer and the second transparent layer after the third step,
In the third step, a first protrusion extending around each of the reflective region and the transmissive region is formed on the second transparent layer,
Forming a first subpixel electrode on the second transparent layer in the reflective region; and forming a second subpixel electrode on the first transparent layer in the transmissive region. And the first subpixel electrode and the second subpixel electrode are formed so as to be surrounded by the first protrusion.
And a step of forming a plurality of scanning lines for supplying gate signals to the TFT, and a step of forming a plurality of signal lines for supplying display signals to the TFT,
Each of the plurality of pixels is disposed between two adjacent ones of the plurality of scanning lines and two adjacent ones of the plurality of signal lines;
In the third step, the first protrusion is formed on the two adjacent scanning lines and the two adjacent signal lines and in a region between the reflection region and the transmission region. 15. The production method according to 15.
The manufacturing method according to claim 15 or 16, wherein in the third step, the first protrusion is formed by overlapping the second transparent layer on the first transparent layer.
And a step of forming a protective layer on the TFT; and a step of forming a color filter including an opening or a depression on the protective layer.
In the second step, a part of the first transparent layer is formed in the opening or the depression,
The said 1st processus | protrusion is formed in the said 3rd process, The said 1st protrusion is formed by forming a part of said 2nd transparent layer on the said 1st transparent layer. The manufacturing method as described in.
In the third step, the second transparent layer includes a first central protrusion that protrudes from the first protrusion at a central portion of the reflective region, and a first protrusion that protrudes from the first protrusion at a central portion of the transmissive region. The manufacturing method according to claim 15, wherein two central protrusions are formed.
The manufacturing method according to claim 19, wherein in the third step, the first central protrusion and the second central protrusion are formed by forming the second transparent layer on the first transparent layer.
In the step of forming the scanning line, an auxiliary capacitance line extending through the reflection region is formed,
The manufacturing method according to claim 16, wherein a reflection layer is formed on the auxiliary capacitance line in the step of forming the signal line.
An opening or a depression is formed in the portion of the auxiliary capacitance line,
The manufacturing method according to claim 21, wherein unevenness reflecting the opening or the depression of the auxiliary capacitance line is formed in the reflective layer.
The manufacturing method according to any one of claims 15 to 22, wherein the TFT substrate is formed using nine photomasks.